The stabilization of zirconia in the cubic phase at room temperature has been known for many years. More recently several articles and patents have appeared, describing a stabilized sintered product (PSZ) which contains both the cubic phase and the monoclinic phase or a metastable tetragonal phase, at room temperature. Also described in the literature are polycrystalline tetragonal zirconia bodies (TZP). The strongest reported material of this type has been described by Garvie in U.S. Pat. No. 4,067,745. That patent discloses a sintered body of relatively coarse cubic crystals containing a precipitate of metastable very fine tetragonal crystals.
U.S. Pat. Nos. 4,344,904 and 4,360,598 also disclose sintered partially stabilized zirconia sintered products.